20781897 has 8 divisors (see below), whose sum is σ = 27730560. Its totient is φ = 13843920.

The previous prime is 20781889. The next prime is 20781931. The reversal of 20781897 is 79818702.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20781897 - 2³ = 20781889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20781697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5104 + ... + 8222.

It is an arithmetic number, because the mean of its divisors is an integer number (3466320).

Almost surely, 2^20781897 is an apocalyptic number.

It is an amenable number.

20781897 is a deficient number, since it is larger than the sum of its proper divisors (6948663).

20781897 is a wasteful number, since it uses less digits than its factorization.

20781897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5343.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 20781897 is about 4558.7165957098. The cubic root of 20781897 is about 274.9339654119.

The spelling of 20781897 in words is "twenty million, seven hundred eighty-one thousand, eight hundred ninety-seven".